Sea-level rise versus salt marsh colonization: The adversarial game of self-organized elevation maintenance in tidal marsh.

Tidal marshes globally face escalating threats from rising sea levels. As critical determinants of tidal marsh platform elevation maintenance, the contributions of marsh soil compaction and subsidence (SCS) are often overshadowed by vertical accretion (VA). Here, we reveal the pervasive presence of the SCS within tidal marshes and its driving forces. Our results demonstrate that while vegetated regions can organize more efficient sediment accumulation, thereby promoting marsh elevation rise, they also contribute to an increase in SCS occurrences, which somewhat hinders marsh elevation growth. Through the established empirical model of SCS, we found that the amount of SCS in the investigated marshes with vegetation cover is twice that of marshes without vegetation. Therefore, from the perspective of SCS, it is imperative to account for the detrimental impact of vegetation on marsh elevation, as we have uncovered that this oversight may lead to an underestimation of the vulnerability of the investigated tidal marsh ecosystem by approximately 13.55 %. We also find that the adversarial game between vegetation colonization and sea-level rise governs the SCS in the self-organization of tidal marshes, but the intensifying inundation from sea-level rise ultimately determines the fate of the SCS. Our study emphasizes the crucial role of the game between sea-level rise and vegetation colonization in the self-organized elevation maintenance of tidal marshes.